| CPC C01B 32/192 (2017.08) [C01B 32/198 (2017.08); C01B 2204/04 (2013.01); C01B 2204/24 (2013.01); C01B 2204/26 (2013.01); C01P 2002/82 (2013.01); C01P 2004/03 (2013.01); C01P 2006/10 (2013.01); C01P 2006/32 (2013.01)] | 6 Claims |
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1. A preparation method of a super-flexible high thermal conductive graphene film, the preparation method comprising steps of:
(1) preparing graphene oxide sheets with an average size of more than 100 μm into a graphene oxide aqueous solution with a concentration in a range of 6-30 mg/mL, adding an additive with a mass fraction of 0.1-5% into the aqueous solution, wherein the additive is inorganic salt, small organic molecule or macromolecule; pouring the aqueous solution added with the additive onto a mold plate after ultrasonic dispersion, obtaining a graphene oxide film by drying the mold plate, and performing reduction on the graphene oxide film through a reducing agent;
(2) increasing a temperature of the reduced graphene film to 500-800° C. at a speed of 0.1-1° C./min and preserving heat for 0.5-2 h under inert gas atmosphere;
(3) after the step (2), increasing the temperature of the reduced graphene to 1000-1300° C. at a speed of 1-3° C./min and preserving heat for 0.5-3 h under inert gas atmosphere;
(4) after the step (3), increasing the temperature of the reduced graphene film to 2500-3000° C. at a speed of 5-8° C./min and preserving heat for 0.5-4 h under inert gas atmosphere; and then naturally decreasing the temperature of the graphene film, and then obtaining a porous graphene film by forming graphene micro-airbags; and
(5) suppressing the graphene micro-airbags and forming wrinkles, thereby obtaining the super-flexible high thermal conductive graphene film which has a density in a range of 1.93 to 2.11 g/cm3 and meets a condition of ID/IG<0.01, here, ID is an intensity of D-peak and IG is an intensity of G-peak,
wherein the graphene oxide sheets with the average size of more than 100 μm are prepared through following steps of:
(A) diluting a reaction solution of the graphite oxide sheets obtained by Modified-Hummer method through concentrated sulfuric acid, wherein a volume of the concentrated sulfuric acid is 1-10 times of the volume of the reaction solution, and obtaining a filtered product by filtering the reaction solution with a mesh screen;
(B) obtaining a mixture by evenly mixing the filtered product obtained in the step (A) with ice water, and dropwise adding hydrogen peroxide into the mixture till a color of the mixture no longer changes which means that potassium permanganate in the mixture is completely removed;
(C) dropwise adding concentrated hydrochloric acid into the mixture added with hydrogen peroxide obtained in the step (B) till flocculent graphite oxide disappears, and then filtering out graphite oxide crystals through the mesh screen; and
(D) peeling off the graphite oxide crystals by placing the graphite oxide crystals obtained in the step (C) into a shaking table, shocking and washing, thereby obtaining the graphene oxide sheets with the average size of more than 100 μm; and
wherein:
the graphene film comprises multiple layers of planar oriented graphene sheets overlapped with each other through π-π conjugate action, wherein each of the multiple layers of planar oriented graphene sheets has an average size of more than 100 μm, each one to four of a partial of the multiple layers of planar oriented graphene sheets form a graphene structure, wherein a debris content of the graphene sheets with the average size of more than 100 μm by mass is lower than 1%; and
the graphene film has wrinkles on a surface and within an interior thereof.
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